/**
 * Process function
 * 
 * @param string $function
 * @param mixed $value
 */
function function2($function, $value)
{
    $result = null;
    switch ($function) {
        case 'date':
        case 'datetime':
        case 'time':
            // todo fix formating
            $result = strtotime($value) !== false ? format::date_format($result['value'], $temp_func, 'system') : '';
            break;
        default:
            $result = $function($value);
    }
    return $result;
}